Sometimes, he would stay in his room and lie in the dark because the pain in his head was so excruciating. And at his darkest moments a few years ago, when it was just about too much to handle, the former Chicago Bears quarterback thought about killing himself.

“I am glad I don’t have any weapons in my house or else I am pretty sure I wouldn’t be here,” McMahon said. “It got to be that bad.”

McMahon opened up about his struggles with early onset dementia and depression, issues he believes were caused by the beating he absorbed playing football, in a gathering with a small group of reporters on Tuesday. He is scheduled to be honoured Wednesday in Chicago by the Sports Legacy Institute, a Boston University-based group that has been studying the effects of brain trauma in athletes and others.

While his suicidal thoughts are a thing of the past thanks to treatment for a fluid blockage in his neck, the fight with dementia continues. The “Punky QB” who once helped the Chicago Bears shuffle their way to a Super Bowl championship is also digging in for another battle, this one with the NFL that could have major consequences for the league.

McMahon is one of several players identified by name in a federal lawsuit filed in California last month accusing teams of illegally dispensing powerful narcotics and other drugs to keep players on the field without regard for their long-term health.

Quarterback Jim McMahon during his days with the Chicago Bears. Jonathan Daniel /Allsport

He is also a party to a concussions-related class-action lawsuit in which the NFL agreed to a $765 million settlement without acknowledging it hid the risks of concussions from former players. A federal judge has yet to approve the settlement, expressing concern the amount is too small.

While McMahon wouldn’t discuss the most recent suit, he did talk about the troubles he has faced in recent years, issues he believes took root when he was getting battered on the field.

McMahon said he had three to five diagnosed concussions and who knows how many more that went undiagnosed. That’s in addition to injuries to the kidney, broken ribs, an addiction to painkillers and a broken neck that he said team doctors and trainers never told him about. He believes that happened when he was with the Minnesota Vikings in 1993.

Jim McMahon says he had three to five diagnosed concussions, but there could have been many more.Jonathan Daniel /Allsport